Tuesday, February 19, 2013

Mutations are random, but evolution may be more predictable than originally thought

Image from science.howstuffworks.com
Life on earth is both ubiquitous and diverse - we're surrounded by somewhere around 8.7 million different species - and the mechanism for how such diversity came about is an interesting question. New research published today suggests that although genetic mutations happen at random, different organisms are able to find the same solution to an environmental pressure.

Genetic diversity can happen when a species is separated and given different environmental pressures. In 2008 Michael Doebeli, evolutionary biologist working at the University of British Columbia, showed genetic diversity in E-Coli occurs even when two strains are in the same environment. In an environment of glucose and acetate, one strain of E-Coli evolved to quickly change between digesting glucose to digesting acetate while another strain made the transition much more slowly. Since publishing those results Doebeli has been studying how this diversification happened. 

They did this by analyzing 17 gene samples from E-Coli that had been frozen at different stages of the initial experiment. This allowed them to see which mutations happened and in what order. Interestingly, even though the strains adapted to their environment at different times they adapted in the same way. In other words, even though the mutations are random the bacteria found the same solution to their hunger woes. Since evolution is not a guided process (mutations are random) these results are surprising. It seems that bacteria in a specific environment will evolve in a more predictable manner than originally thought.